Heat exchanger and air conditioner incorporating same

ABSTRACT

A heat exchanger ( 1 ) includes: two vertical header pipes ( 2, 3 ) which are arranged apart in parallel; a plurality of flat tubes ( 4 ) which are arranged between the header pipes and in which refrigerant passages ( 5 ) provided therewithin communicate with an interior of the header pipes; and corrugated fins ( 6 ) which are arranged between the flat tubes. The flat tubes are configured to form one or more turns. In the header pipe on the refrigerant piping connection side, a temperature sensor ( 11 ) for sensing the temperature of a refrigerant is arranged at a location through which the refrigerant in a gas-liquid two-phase state flows. The temperature sensor is attached to the header pipe with a metal fitting ( 12 ).

TECHNICAL FIELD

The present invention relates to a side-flow-type parallel flow heat exchanger and an air conditioner incorporating such a side-flow-type parallel flow heat exchanger.

BACKGROUND ART

A parallel flow heat exchanger in which a plurality of flat tubes are arranged between two header pipes, a plurality of refrigerant passages within the flat tube communicate with the interior of the header pipes and a fin such as a corrugated fin is arranged between the flat tubes is widely used in automobile air conditioners and building air conditioners. Examples of this type of heat exchanger are disclosed in patent documents 1 and 2.

In an air conditioner, an operation is controlled based on the temperature of a heat exchanger where a refrigerant flows, and this technical means is commonly used. An example of such an air conditioner is disclosed in patent document 3.

In general, in the heat exchanger of an indoor unit in an air conditioner, as disclosed in patent document 4, auxiliary piping connected to an outdoor unit is provided. It is necessary to connect not only refrigerant piping but also a power supply line and a signal line to the outdoor unit. In general, an electrical component box holding a control board to which the power supply line and the signal line are connected and the like is arranged next to the auxiliary piping so that the power supply line and the signal line are easily put together with the refrigerant piping.

In a parallel flow heat exchanger, a plurality of flat tubes are divided into a few groups, a refrigerant is passed through a first group of flat tubes from a first header pipe to a second header pipe, then the refrigerant is returned through a second group of flat tubes from the second header pipe to the first header pipe and the refrigerant is passed again through a third group of flat tubes from the first header pipe to the second header pipe. As described above, the refrigerant is often passed along a zigzag route. As disclosed in patent document 2, the number of times the direction of flow of the refrigerant is changed between the first header pipe and the second header pipe is referred to as the “number of turns.”

RELATED ART DOCUMENT Patent Document

Patent document 1: JP-A-S63-34466

Patent document 2: JP-A-H6-213534

Patent document 3: JP-A-2009-41829

Patent document 4: JP-A-2000-297948

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In an air conditioner, in order to ensure safety at the time of operation, it is necessary to find the pressure within a heat exchanger and perform control based on the resulting information. Practically, instead of directly measuring the pressure, the pressure is estimated by measuring the temperature of a refrigerant.

When a heat exchanger is used as a condenser, a refrigerant in an overheated gaseous state flows in, is then changed into a gas-liquid two-phase state as heat exchange proceeds and is changed into a supercooled state and then a liquid state as condensation further proceeds. The temperature of the refrigerant differs depending on its state, that is, the gaseous sate, the gas-liquid two-phase state and the liquid state. In order to estimate the pressure, it is necessary to measure the temperature of the refrigerant in the gas-liquid two-phase state in which the temperature is stable.

An object of the present invention into make the temperature of a refrigerant to measured useful for control in a so-called side-flow-type parallel flow heat exchanger where the refrigerant flows through horizontal flat tubes.

Means for Solving the Problem

To achieve the above object, according to the present invention, there is provided a side-flow-type parallel flow heat exchanger that includes: two header pipes which are arranged apart in parallel; and a plurality of flat tubes which are arranged between the two header pipes and in which refrigerant passages provided therewithin communicate with an interior of the header pipes, in which the flat tubes are configured to form one or more turns, and, in one of the two header pipes, a temperature sensor for sensing the temperature of a refrigerant is arranged at a location through which the refrigerant in a gas-liquid two-phase state flows.

In this configuration, the temperature of the refrigerant in the gas-liquid two-phase state which can be regarded as a refrigerant condensation temperature or a refrigerant vaporization temperature is measured, and thus it is possible to accurately estimate the pressure of the refrigerant.

In the heat exchanger configured as described above, the header pipe at which the temperature sensor is arranged is preferably the header pipe on the refrigerant piping connection side.

When an air conditioner is composed of an outdoor unit and an indoor unit, in general, refrigerant piping and power supply wiring or signal wires are put together and piping and wiring are performed thereon. When the temperature sensor is arranged at the header pipe on the side of the refrigerant wiring, it is possible to easily wire the temperature sensor and reduce the length of the wiring and the cost of materials.

In the heat exchanger configured as described above, the number of turns is preferably set at an odd number of three or more.

When the number of turns is set as described above, the entrance and the exit of the refrigerant are arranged in the same header pipe, and thus it is possible to acquire a portion of the header pipe through which the refrigerant in the gas-liquid two-phase state flows.

In the heat exchanger configured as described above, the temperature sensor is preferably attached to the header pipe with a metal fitting including a temperature sensor insertion portion and a header pipe holding portion.

With this configuration, it is possible to easily attach the temperature sensor without the need to process the header pipe.

According to the present invention, there is provided an air conditioner in which the heat exchanger configured as described above is incorporated in an indoor unit.

With this configuration, it is possible to provide an air conditioner that can appropriately perform control to accurately estimate the pressure of the refrigerant in the heat exchanger of the indoor unit.

According to the present invention, there is provided an air conditioner in which the heat exchanger configured as described above is incorporated in an outdoor unit.

With this configuration, it is possible to provide an air conditioner that can appropriately perform control to accurately estimate the pressure of the refrigerant in the heat exchanger of the outdoor unit.

Advantages of the Invention

According to the present invention, it is possible to accurately estimate the pressure of a refrigerant flowing through a heat exchanger, with the result that various types of control can be reliably performed. The detection of abnormality when the air conditioner is operated is easily performed.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A schematic vertical cross-sectional view of a heat exchanger illustrating an embodiment of the present invention;

[FIG. 2] A vertical cross-sectional view of the heat exchanger taken along line A-A of FIG. 1;

[FIG. 3] A partial front view of the heat exchange illustrating a method of attaching a temperature sensor;

[FIG. 4] A front view of a metal fitting for attaching the temperature sensor;

[FIG. 5] A top view of the metal fitting for attaching the temperature sensor;

[FIG. 6] A schematic diagram showing the configuration of an air conditioner incorporating the heat exchanger according to the present invention, and showing a state where a heating operation is performed; and

[FIG. 7] A schematic diagram showing the configuration of the air conditioner incorporating the heat exchanger according to the present invention, and showing a state where a cooling operation is performed.

MODE FOR CARRYING OUT THE INVENTION

The structure of a side-flow-type parallel flow heat exchanger according to an embodiment of the present invention will be described with reference to FIG. 1. In FIG. 1, the upper side of the plane of the figure is the upper side of the actual heat exchanger, and the lower side of the plane of the figure is the lower side of the actual heat exchanger. In the heat exchanger 1, two vertical header pipes 2 and 3 are arranged apart in a horizontal direction in parallel, and a plurality of horizontal flat tubes 4 are arranged between the header pipes 2 and 3 in a vertical direction with a predetermined pitch. The flat tube 4 is a long slender component that is formed by extruding metal, and refrigerant passages 5 for circulating a refrigerant are formed within the flat tube 4. Since the flat tubes 4 are arranged such that the direction of extrusion, which is the longitudinal direction of the flat tubes 4, is horizontal, the direction of circulation of the refrigerant in the refrigerant passage 5 is also horizontal. A plurality of refrigerant passages 5 that have the same cross-sectional shape and the same cross-sectional area are arranged in the depth direction of FIG. 1, and thus the cross section of the flat tube 4 is in the shape of a harmonica, as shown in FIG. 2. Each of the refrigerant passages 5 communicates with the interior of the header pipes 2 and 3. A corrugated fin 6 is arranged between the adjacent flat tubes 4. Among the vertically arranged corrugated fins 6, a side plate 10 is arranged on the outside of each of the uppermost corrugated fin 6 and the lowermost corrugated fin 6.

Each of the header pipes 2 and 3, the flat tube 4, the corrugated fin 6 and the side plate 10 is formed of a meal, such as aluminum, having a good thermal conductivity. The flat tubes 4, the corrugated fins 6 and the side plates 10 are fixed, by brazing or welding, to the header pipes 2 and 3, the flat tubes 4 and the corrugated fins 6, respectively.

The heat exchanger 1 is a side flow type, and refrigerant ports 7 and 8 are provided only on the side of the header pipe 3. In other words, the header pipe 3 is a header pipe on the refrigerant piping connection side. Within the header pipe 3, two partitions 9 a and 9 c are arranged apart in the vertical direction; within the header pipe 2, a partition 9 b is provided at the midpoint between the partitions 9 a and 9 c in height.

When the heat exchanger 1 is used as a condenser, as indicated by a solid arrow line, the refrigerant flows in through the refrigerant port 7 on the upper side. The refrigerant that has flowed in through the refrigerant port 7 is blocked by the partition 9 a, and flows toward the header pipe 2 through the flat tubes 4. The flow of the refrigerant is represented by a leftward pointing block arrow. The refrigerant that has flowed into the header pipe 2 is blocked by the partition 9 b, and flows toward the header pipe 3 through other flat tubes 4. This is the first turn, and the flow of the refrigerant after the turn is represented by a rightward pointing block arrow. The refrigerant that has flowed into the header pipe 3 is blocked by the partition 9 c, and flows again toward the header pipe 2 through yet other flat tubes 4. This is the second turn, and the flow of the refrigerant after the turn is represented by a leftward pointing block arrow. The refrigerant that has flowed into the header pipe 2 is returned, and flows again toward the header pipe 3 through yet another flat tube 4. This is the third turn, and the flow of the refrigerant after the turn is represented by a rightward pointing block arrow. The refrigerant finally flows out through the refrigerant port 8.

As described above, the refrigerant flows from top to bottom along a zigzag route while making turns repeatedly. The case where the number of partitions is three has been described above; this is an example. The number of partitions and the resulting number of turns can be set at arbitrary numbers as necessary.

In the configuration of FIG. 1, a plurality of flat tubes 4 arranged in a region of height between the refrigerant port 7 and the partition 9 a constitute a flow passage, a plurality of flat tubes 4 arranged in a region of height between the partition 9 a and the partition 9 b constitute another flow passage, a plurality of flat tubes 4 arranged in a region of height between the partition 9 b and the partition 9 c constitute yet another flow passage and a plurality of flat tubes 4 arranged in a region of height between the partition 9 c and the refrigerant port 8 constitute yet another flow passage. These flow passages are referred, in the order in which they have been described, to as a “first flow passage,” a “second flow passage,” a “third flow passage” and a “fourth flow passage.”

When the heat exchanger 1 is used as an evaporator, the flow of the refrigerant is reversed. Specifically, the refrigerant flows into the header pipe 3 through the refrigerant port 8 as indicated by a dotted arrow of FIG. 1, is blocked by the partition 9 c and flows toward the header pipe 2 through the fourth flow passage, is blocked by the partition 9 b in the header pipe 2 and flows toward the header pipe 3 through the third flow passage, is blocked by the partition 9 a in the header pipe 3 and flows again toward the header pipe 2 through the second flow passage, is returned in the header pipe 2 and flows again toward the header pipe 3 through the first flow passage and flows out through the refrigerant port 7.

A temperature sensor 11 obtained by sealing a thermistor in a metallic case is attached so as to measure the temperature of the refrigerant flowing within the heat exchanger 1. The temperature sensor 11 is arranged at a location corresponding to the second flow passage and the third flow passage within the header pipe 3. This location is selected for the following reason.

When the heat exchanger 1 is used as a condenser, the refrigerant in an overheated state flows in through the refrigerant port 7 on the upper side, and the refrigerant here is in a gaseous state. Thereafter, as thermal exchange proceeds through the first flow passage, the refrigerant is changed into a gas-liquid two-phase state, and gradually condenses. In the vicinity of the exit of the fourth flow passage through which the refrigerant flows out, the refrigerant is in a supercooled state, and is liquid. Since the temperature (two-phase temperature) of the refrigerant in the gas-liquid two-phase state can be regarded as a refrigerant condensation temperature or a refrigerant vaporization temperature, and is suitable as a reference temperature for control, the temperature sensor 11 is arranged at a location where the two-phase temperature can be measured.

When the heat exchanger 1 is used as an evaporator, the refrigerant in the gas-liquid two-phase state flows in through the refrigerant port 8 on the lower side. Thereafter, thermal exchange proceeds with the refrigerant in the gas-liquid two-phase state, and the refrigerant gradually vaporizes. In the vicinity of the exit of the first flow passage through which the refrigerant flows out, the refrigerant is either in the gas-liquid two-phase state or in the gaseous state. Since the temperature (the two-phase temperature) of the refrigerant in the gas-liquid two-phase state can be regarded as the refrigerant vaporization temperature, and is suitable as the reference temperature for control, the temperature sensor 11 is arranged at a location where the two-phase temperature can be measured.

As described previously, in the heat exchanger of an indoor unit in an air conditioner, auxiliary piping connected to an outdoor unit is provided. It is necessary to connect not only refrigerant piping but also a power supply line and a signal line to the outdoor unit. In general, an electrical component box holding a control board to which the power supply line and the signal line are connected and the like is arranged next to the auxiliary piping so that the power supply line and the signal line are easily put together with the refrigerant piping. Since the temperature sensor 11 is wired from the electrical component box described above, with consideration given to the length of the wiring, it is preferable to attach the temperature sensor 11 to the side of the auxiliary piping of the heat exchanger 1.

In the heat exchanger 1 that is the side-flow-type parallel flow heat exchanger, the header pipe 3 is a header pipe on the refrigerant piping connection side, and not only the refrigerant piping but also the power supply wiring and the signal line are nearby. Hence, the temperature sensor 11 is attached to the header pipe 3, and the temperature sensor 11 is arranged at the location (preferably the midpoint between the partition 9 a and the partition 9 c) corresponding to the second turn.

Consider now the number of turns. If there is only one turn, when the heat exchanger 1 is used as a condenser, refrigerant entrance piping and refrigerant exit piping are connected to one of the header pipes, and, on the refrigerant entrance side, the header pipe is filled with the refrigerant in the overheated state, and, on the refrigerant exit side, the header pipe is filled with the refrigerant in the supercooled state, with the result that the refrigerant in the gas-liquid two-phase state cannot be present in the header pipe. When the heat exchanger 1 is used as a condenser, the number of turns is preferably an odd number of three or more such that conditions under which the refrigerant in the gas-liquid two-phase state can be present and the refrigerant flowing from the header pipe on the refrigerant piping connection side is finally returned to the header pipe on the refrigerant piping connection side are satisfied. In the embodiment, three, that is the number of turns, is a number that satisfies the minimum requirement.

The temperature sensor 11 is attached to the header pipe 3 with a metal fitting 12 shown in FIGS. 3 to 5. The metal fitting 12 is formed of a steel plate having a good spring characteristic, and includes: a temperature sensor insertion portion 13 to which the temperature sensor 11 is press-fitted; and a header pipe holding portion 14 which holds the header pipe 3. In the entrance portion of the header pipe holding portion 14, a pair of guide parts 15 is formed that extends and tapers to guide the header pipe 3.

In a portion of the temperature sensor insertion portion 13 that is farthest from the header pipe holding portion 14, a bending portion 16 having a small radius is formed. The bending portion 16 helps to maintain the holding force of the metal fitting 12.

In the boundary between the temperature sensor insertion portion 13 and the header pipe holding portion 14, a holding part 17 is formed that is curved along the outer surface of the temperature sensor 11. The holding part 17 functions to hold the temperature sensor 11, and also functions to prevent the temperature sensor 11 from making contact with the header pipe 3. As the material of the metallic case of the temperature sensor 11, copper is often used because copper has excellent thermal conductivity and is easily processed; when copper makes contact with the header pipe 3 made of aluminum, there is a danger that the aluminum corrodes by electrical corrosion and thus a hole is formed in the header pipe 3. When the holding part 17 is present, it intervenes between the header pipe 3 and the temperature sensor 11, and thus it is possible to prevent the aluminum from making contact with the copper, with the result that the electrical corrosion can be avoided.

The heat exchanger 1 can be incorporated in a separate-type air conditioner. The separate-type air conditioner is composed of an outdoor unit and an indoor unit; the outdoor unit includes a compressor, a four-way valve, an expansion valve, an outdoor heat exchanger and an outdoor blower; the indoor unit includes an indoor heat exchanger and an indoor blower. The outdoor heat exchanger functions as an evaporator when a heating operation is performed, and also functions as a condenser when a cooling operation is performed. The indoor heat exchanger functions as a condenser when a heating operation is performed, and also functions as an evaporator when a cooling operation is performed.

The basic configuration of a separate-type air conditioner using a heat pump cycle as a refrigeration cycle is shown in FIG. 6. The heat pump cycle 101 is formed by connecting, in a loop, a compressor 102, a four-way valve 103, an outdoor heat exchanger 104, a decompression expansion device 105 and an indoor heat exchanger 106. The compressor 102, the four-way valve 103, the heat exchanger 104 and the decompression expansion device 105 are housed in the enclosure of an outdoor unit; the heat exchanger 106 is housed in the enclosure of an indoor unit. The heat exchanger 104 is combined with an outdoor blower 107; the heat exchanger 106 is combined with an indoor blower 108. The blower 107 includes a propeller fan; the blower 108 includes a cross-flow fan.

The side-flow-type parallel flow heat exchanger of the present invention can be used as the indoor heat exchanger 106. In the heat exchanger 106, the two heat exchangers 1 are combined so as to be dogleg-shaped.

FIG. 6 shows a state when a heating operation is performed. Here, the refrigerant of high temperature and high pressure discharged from the compressor 102 enters the heat exchanger 106, where the refrigerant emits heat and condenses. The refrigerant that has flowed out of the heat exchanger 106 enters, through the decompression expansion device 105, the outdoor heat exchanger 104, where the refrigerant expands. Then, the refrigerant takes in heat from outdoor air, and thereafter returns to the compressor 102. An air current generated by the indoor blower 108 facilitates the discharge of the heat from the heat exchanger 106; an air current generated by the outdoor blower 107 facilitates the absorption of the heat by the heat exchanger 104.

FIG. 7 shows a state when a cooling operation or a defrosting operation is performed. Here, the four-way valve 103 is switched, and the flow of the refrigerant is reversed as compared with the case where a heating operation is performed. Specifically, the refrigerant of high temperature and high pressure discharged from the compressor 102 enters the heat exchanger 104, where the refrigerant emits heat and condenses. The refrigerant that has flowed out of the heat exchanger 104 enters, through the decompression expansion device 105, the indoor heat exchanger 106, where the refrigerant expands. Then, the refrigerant takes in heat from indoor air, and thereafter returns to the compressor 102. The air current generated by the outdoor blower 107 facilitates the discharge of the heat from the heat exchanger 104; the air current generated by the indoor blower 108 facilitates the absorption of the heat by the heat exchanger 106.

As described above, the heat exchanger 1 is used as the indoor heat exchanger 106, and thus it is possible to accurately estimate the pressure of the refrigerant flowing through the heat exchanger 106, with the result that various types of control can be reliably performed. The detection of abnormality when the air conditioner is operated is easily performed.

The heat exchanger 1 can also be used as the outdoor heat exchanger 104. In this way, it is also possible to accurately estimate the pressure of the refrigerant flowing through the heat exchanger 104, with the result that various types of control can be reliably performed. The detection of abnormality when the air conditioner is operated is easily performed.

Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to the embodiment. Many modifications are possible without departing from the spirit of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is widely utilized as a side-flow-type parallel flow heat exchanger.

LIST OF REFERENCE SYMBOLS

1 heat exchanger

2, 3 header pipe

4 flat tube

5 refrigerant passage

6 corrugated fin

9 a, 9 b, 9 c partition

11 temperature sensor

12 metal fitting 

1. A side-flow-type parallel flow heat exchanger that includes: two header pipes which are arranged apart in parallel; and a plurality of flat tubes which are arranged between the two header pipes and in which refrigerant passages provided therewithin communicate with an interior of the header pipes, wherein the flat tubes are configured to form one or more turns, and, in one of the two header pipes, a temperature sensor for sensing a temperature of a refrigerant is arranged at a location through which the refrigerant in a gas-liquid two-phase state flows.
 2. The heat exchanger of claim 1, wherein the header pipe at which the temperature sensor is arranged is the header pipe on a refrigerant piping connection side.
 3. The heat exchanger of claim 2, wherein a number of turns is set at an odd number of three or more.
 4. The heat exchanger of claim 1, wherein the temperature sensor is attached to the header pipe with a metal fitting including a temperature sensor insertion portion and a header pipe holding portion.
 5. An air conditioner wherein the heat exchanger of claim 1 is incorporated in an indoor unit.
 6. An air conditioner wherein the heat exchanger of claim 1 is incorporated in an outdoor unit.
 7. The heat exchanger of claim 2, wherein the temperature sensor is attached to the header pipe with a metal fitting including a temperature sensor insertion portion and a header pipe holding portion.
 8. The heat exchanger of claim 3, wherein the temperature sensor is attached to the header pipe with a metal fitting including a temperature sensor insertion portion and a header pipe holding portion. 